How can I add letters on cube?
Make a new window and change it to UV/Image editor
In the 3D view go to edit mode and select the face u want fix the texture and press U and select Unwrap
Go to the Properties panel next to material there is texture layout
Below in type change to image or movie
And in the Image open the image as shown in .gif
Now in the UV Editor Select the image u want to focus from drop down.
And in the 3D change from solid to texture.